Method of making a tool component

ABSTRACT

In a method of producing a tool component a plurality of fibres is formed into a bundle. Each fibre has a core comprising a mass of ultra-hard abrasive particles or precursor to said ultra-hard abrasive particles and optionally a second phase, and a coating comprising a mixture of carbide particles and particulate binder metal. After extruding the bundle of fibres, the bundle is severed transverse to its length to produce a layer. The layer is placed on a surface of a substrate and the layer and substrate are subjected to elevated temperature and pressure conditions at which the ultra-hard abrasive particles are crystallographically stable. The composition of the core and coating may be interchanged in the method.

BACKGROUND OF THE INVENTION

This invention relates to a method of making a tool component.

Tool components utilising diamond compacts, also known as PCD, and cubicboron nitride compacts, also known as PCBN, are extensively used indrilling, milling, cutting and other such abrasive applications. Thetool component will generally comprise a layer of PCD or PCBN bonded toa support, generally a cemented carbide support. The PCD or PCBN layermay present a sharp cutting edge or point or a cutting or abrasivesurface.

U.S. Pat. No. 6,063,502 describes a material useful for producing theabrasive layer of a tool component. The material comprises a firststructural phase comprising a hard material selected from the groupconsisting of cemented carbide materials, PCD, PCBN and mixturesthereof, and a second structural phase comprising a material that isdifferent to that used to form the first structural phase, the secondstructural phase being in contact with at least a portion of the firststructural phase. The material includes repeated structural units,disposed across a working surface of the material, each unit comprisingan ordered micro-structure of the first and second structural phases. Inuse, this material is applied to a surface of a substrate and thenbonded to that substrate.

This United States patent describes various methods of producing thematerial. One such method comprises producing a plurality of fibreshaving a core of the first structural phase and a coating of the secondstructural phase, orienting the fibres parallel to a common axis andthen extruding them into a rod. The extruded rod can be cut into adesired geometry for the tool component or sliced to form a cuttingsurface for placement on to a substrate.

SUMMARY OF THE INVENTION

According to the present invention, a method of producing a toolcomponent includes the steps of:

-   -   (1) providing a plurality of fibres, each fibre having a core        comprising a mass of ultra-hard abrasive particles or precursor        to said ultra-hard abrasive particles and optionally a second        phase, and a coating comprising a mixture of carbide particles        and particulate binder metal,    -   (2) producing a bundle of the fibres,    -   (3) severing the bundle transverse to its length to produce a        layer,    -   (4) placing the layer on a surface of a substrate, and    -   (5) subjecting the layer and substrate to elevated temperature        and pressure conditions at which the ultra-hard abrasive        particles are crystallographically stable.

The composition of the core and coating may be interchanged in themethod described above. Such a method forms another aspect of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 6 illustrate schematically steps in an embodiment of theinvention.

DESCRIPTION OF EMBODIMENTS

In accordance with the method of producing a tool component of theinvention a plurality of fibres is provided, each fibre having a corewhich is coated. For convenience, the invention will be described withreference to the core consisting of a mass of ultra-hard particles orprecursor to said ultra-hard abrasive particles and the coatingconsisting of carbide particles and particulate binder metal. It is tobe understood that the components of the core and coating may beinterchanged.

A bundle is formed of the fibres, which is then severed transverse toits length to produce a layer. The layer is then applied to a surface ofa substrate, whereafter the layer and substrate are subjected toconditions of elevated temperature and pressure at which the ultra-hardabrasive particles are crystallographically stable.

The product which is produced is a tool component comprising thesubstrate having a working portion produced from the layer bonded to asurface thereof. The working portion comprises a composite materialcomprising essentially a honeycomb structure of cemented carbide andabrasive compact material within the pores of the honeycomb structureand bonded to the honeycomb structure. The pores of the honeycombstructure may be ordered or random.

The ultra-hard abrasive particles will generally be diamond or cubicboron nitride. Thus, the abrasive compact which is produced in the poresof the honeycomb structure will preferably be PCD or PCBN. That PCD orPCBN will preferably contain a second phase which will typically be asolvent/catalyst for the ultra-hard abrasive particles.

The particulate components of the core and coating of the fibres willpreferably be in bonded form using a bonding agent such as an organicbinder. An example of a particularly suitable binder is methylcellulose. Generally, this binder will be removed, e.g. by heating,prior to subjecting the substrate and layer to the elevated temperatureand pressure conditions.

The carbide particles of the coating will typically be tungsten carbideparticles, tantalum carbide particles or molybdenum carbide particles.The metal binder may be any metal binder known in the art such as iron,nickel, cobalt or an alloy containing one or more of these metals.

The coating may comprise one or more layers. In the case that thecoating comprises more than one layer, each layer will differ from theadjacent layer or layers in physical and/or chemical properties. Forexample, a particular layer of the coating may contain coarser or finercarbide particles than the adjacent layer or layers. Alternatively, oradditionally, a particular layer may contain a different metal binder tothat in the layer or layers to which it is adjacent.

The layer which is applied to a surface of the substrate is in a greenstate form. As such, it has a flexibility and may be applied to surfaceswhich are flat or profiled, e.g. a curved surface. The layer may bemoulded into a shape complimentary to the substrate to which it is to bebonded.

The substrate will typically be a cemented carbide substrate.

An embodiment of the invention will now be described with reference tothe accompanying drawings. Referring first to FIG. 1, there is shown afibre comprising a core 10 and a coating 12. The core 10 comprises amixture of diamond particles and a diamond solven/catalyst, inparticulate form, bonded into coherent form by means of an organicbinder. The coating 12 comprises a mixture of carbide particles andmetal binder, in particulate form, again bonded into coherent form bymeans of an organic binder.

The fibre of FIG. 1 is reduced in cross-section by extruding it throughnozzle 14 (see FIG. 2). A plurality of the fibres 16 extruded throughnozzle 14 form a bundle 18. The bundle 18 is then further extrudedthrough nozzle 14 as shown in FIG. 4. The extruded product is a rod 20comprising the fibres 16 pressed into each other, as shown in FIG. 5.This rod 20 may then be severed in a direction transverse to its length,as shown by the dotted lines 22. The severed piece or layer 24 may beremoved. Thus, the layer 24, which has flexibility, may be placed on thecurved surface 26 of a substrate 28, as shown in section by FIG. 6.

The green state product of FIG. 6 is placed in a suitable capsule forinsertion into the reaction zone of a conventional high temperature/highpressure apparatus. The organic binder is first removed by heating thecapsule to drive off the binder. The capsule is then placed in thereaction zone and the contents of the capsule subjected to diamondsynthesis conditions. Typically, the pressure applied will be of theorder of 4 to 8 GPa and the temperature will be of the order of 1300° C.to 1700° C. This has the effect of producing PCD out of the material ofcore 10 and cemented carbide out of the material of coating 12. The PCDwill be bonded to the cemented carbide. The layer 24 will be bonded tothe surface 26 of the substrate 28 producing a working portion for thetool component. The working portion will have a honeycomb structure,similar to that shown by FIG. 6, of cemented carbide and PCD within thepores of the honeycomb structure.

Although not present in this embodiment, if desired, an interlayer maybe provided between the layer 24 and the surface 26 of the substrate 28.Such an interlayer would be selected to provide intermediate propertiesfor stress management at the interface between the layer 24 and thesubstrate surface 26.

1. A method of producing a tool component including the steps of: (1)providing a plurality of fibres, each fibre having a core comprising amass of ultra-hard abrasive particles or precursor to said ultra-hardabrasive particles and optionally a second phase, and a coatingcomprising a mixture of carbide particles and particulate binder metal,(2) producing a bundle of the fibres, (3) severing the bundle transverseto its length to produce a layer, (4) placing the layer on a surface ofa substrate, and (5) subjecting the layer and substrate to elevatedtemperature and pressure conditions at which the ultra-hard abrasiveparticles are crystallographically stable.
 2. A method according toclaim 1, wherein the bundle of fibres is extruded prior to being severedto produce the layer.
 3. A method according to claim 1, wherein the corecomprises a mixture of diamond or cubic boron nitride particles and anappropriatesolvent/catalyst, in particulate form, bonded into a coherentform by means of an organic binder.
 4. A method according to claim 1,wherein the coating is bonded into a coherent form by means of anorganic binder.
 5. A method according to claim 1, wherein the carbideparticles are tungsten carbide particles, tantalum carbide particles ormolybdenum carbide particles.
 6. A method according to claim 1, whereinthe substrate is a cemented carbide substrate.
 7. A method according toclaim 1, wherein the coating comprises one or more layers.
 8. A methodaccording to claim 7, wherein the coating comprises more than one layer,each layer differing from an adjacent layer in physical and/or chemicalproperties.
 9. A method according to claim 8, wherein one layer hascoarser or finer carbide particles than the adjacent layer (s) orcontains a different metal binder to that in the adjacent layer (s). 10.A method according to claim 1, wherein the tool component comprising thesubstrate has a working portion produced from the layer bonded to asurface thereof.
 11. A method according to claim 10, wherein the workingportion comprises a composite material comprising essentially ahoneycomb structure of cemented carbide and abrasive compact materialwithin the pores of the honeycomb structure and bonded to the honeycombstructure.
 12. A method according to claim 11, wherein the pores of thehoneycomb structure are ordered or random.
 13. A method of producing atool component including the steps of: (1) providing a plurality offibres, each fibre having a core comprising a mixture of carbideparticles and particulate binder metal, and a coating comprising a massof ultra-hard abrasive